The design and installation of automatic fire sprinkler protection systems is dependent upon several factors including: the area to be protected, the occupants or items to be protected in the area being protected, the manner in which a fire is to be addressed. One particular area of interest is automatic fire protection systems for the protection of the following types of storage arrangements: palletized storage, solid pile storage, shelf storage, bin-box storage, or rack storage and more particularly for the protection of such storage in excess of twelve feet of height, i.e., high-piled storage. Fire protection systems for rack storage generally include a gridded arrangement of spaced apart automatic fire protection sprinklers installed above the rack storage and beneath the ceiling of the storage occupancy, i.e., ceiling-level sprinklers, which are connected to a supply of firefighting fluid by a network of pipes to distribute the fluid upon actuation in response to a fire. The rack storage systems can be configured with only ceiling-level sprinklers, i.e., a “ceiling-only” system or alternatively can include ceiling-level and face sprinklers installed in the rack, i.e., “in-rack” sprinklers, or along the aisle face of the storage. As used herein, “ceiling-only” fire protection is where the water or other fire suppressant is exclusively applied from ceiling-level sprinklers and therefore do not include in-rack sprinklers.
Fire protection installations are generally subject to industry accepted fire code requirements and the approval of the “authority having jurisdiction” (AHJ) to ensure compliance with the applicable codes and requirements. For example, one applicable standard is “NFPA 13: Standard for the installation of Sprinkler Systems” (2016) (“NFPA 13”) from the National Fire Protection Association (NFPA). NFPA 13 provides the minimum requirements for the design and installation of automatic fire sprinkler systems based upon the area to be protected, the anticipated hazard and the type of protection performance to be provided. Another industry accepted installation standard focused on both safety and property loss is FM Global Property Loss Prevention Data Sheet 8-9 (June 2015, Interim Rev. January 2018) and (March 2010, Interim Rev. July 2018) (collectively “FM 8-9”) from Factory Mutual Insurance Company of FM Global. FM 8-9 provides FM installation guidelines for the protection of Class 1, 2, 3, 4, and plastic commodities maintained in solid-piled, palletized, shelf, bin-box or rack storage arrangements.
NFPA 13 defines the performance of rack storage fire protection systems based upon the manner in which the system and its automatic fire sprinklers are designed to address a fire. For example, a system and its sprinklers can be configured to address a fire with “fire control” as defined under NFPA 13, does so by “limiting the size of a fire by distribution of water so as to decrease the heat release rate and pre-wet adjacent combustibles, while controlling ceiling gas temperatures to avoid structural damage.” Systems and sprinklers can also be alternatively configured for “fire suppression” performance which is defined under NFPA 13 as “sharply reducing the heat release rate of a fire and preventing its regrowth by means of direct and sufficient application of water through the fire plume to the burning fuel surface.” FM 8-9 installation guidelines are designed to provides suppression performance in rack storage protection. As used herein, “suppression mode” systems or sprinklers are defined as systems or components that sharply reduce the heat release rate of a fire and prevent its regrowth by directly and sufficiently applying water or other fire suppressant through the fire plume to the burning fuel source.
Thus, in order to satisfy the requirements for ceiling-only rack storage suppression systems, the ceiling-level sprinklers should be demonstrably capable of suppressing a fire of known size with a minimum number of sprinkler operations located at a desired ceiling-level installation height above the rack storage. Identification and qualifying of fire protection sprinklers capable of such suppression performance can be accomplished by appropriate water distribution and/or full-scale fire testing. As used herein, “qualified for suppression” means the sprinkler has been shown to satisfy full-scale fire testing showing suppression performance, satisfied appropriate water distribution testing for suppression and/or is listed by an appropriate testing agency as having satisfied suppression performance requirements. Through such testing, the system design and installation criteria for the tested sprinklers, for use in accordance with the applicable installation codes and standards, can also be identified. This design criteria can include: (i) the maximum ceiling-height for which ceiling-only protection can be provided; (ii) the hazard classifications and type of storage arrangement that can be protected at the maximum ceiling-height; (iii) the maximum height of the storage to be protected; (iv) the range of spacing between sprinklers installed at the maximum ceiling height and/or (v) the hydraulic design requirements for installing the sprinklers at the maximum height.
Accordingly, under both NFPA and FM installation guidelines, there are several design considerations in the use and installation of ceiling-level sprinklers for rack storage protection. These considerations include: the hazard type or “classification” of the stored commodity, the storage arrangement, the maximum or peak ceiling height, and the characteristics of the sprinkler to be used. Industry accepted commodity hazard classifications, including under FM 8-9 guidelines, segregate materials according to their degree of combustibility. For example, FM 8-9 lists the following commodity classifications in order from lowest hazard to highest hazard: Class 1, Class 2, Class 3, Class 4, cartoned unexpanded plastic, cartoned expanded plastic, uncartoned unexpanded plastic and uncartoned expanded plastic. Accordingly, uncartoned unexpanded and expanded plastic commodities represent the two most challenging fire hazards (“high hazard”), with uncartoned expanded plastic commodities representing the most challenging fire scenario. Under NFPA 13 guidelines, plastic commodities are classified under Group A, Group B-Class IV, or Group C-Class III plastics with Group A plastics being the most combustible or highest hazard. The Group A plastics are separately classifiable as cartoned (unexpanded or expanded) and uncartoned (unexpanded or expanded). Rack storage can have various kinds of commodity arrangements including: single row, double-row or multiple-row arrangements. Additionally, the rack arrangement can be defined by flue spaces and aisle widths between the arranged rows. In addition to the commodity classification or hazard, the rack storage fire protection system criteria under the guidelines are defined by the maximum ceiling height of the occupancy and the maximum height of the storage.
Based upon the various design considerations, the installation standards provide an indicated number of operating or design sprinklers for which a given minimum sprinkler operating pressure is to be provided for the maximum height of the storage and/or ceiling of the occupancy to be protected. The design sprinklers are an identified number of “most hydraulically remote sprinklers.” As used herein the most hydraulically remote sprinklers are those sprinklers that experience the greatest fluid pressure loss relative to the fluid supply source when supplying the sprinklers with the minimum fluid flowing operating pressure for the sprinkler. Under the guidelines, the “design area” of the system is defined by the spacing of the indicated number of design sprinklers multiplied by the sprinklers' spacing or coverage requirements. Because the design area is defined by the identified most hydraulically remote sprinklers, the design area is the “most hydraulic remote area” of the system. As used herein, the most hydraulically remote area means the area that must be proven by hydraulic calculation that if all sprinklers within the design area activate, the piping and supply can provide the required operation pressure and/or fluid flow.
For example, one type of sprinkler for use as a ceiling-level rack storage protection sprinkler is the early suppression faster response (ESFR) sprinkler. NFPA guidelines generally provide that the ESFR sprinkler design areas for rack storage over 25 feet are defined by twelve (12) most hydraulically remote sprinklers, consisting of four sprinklers on each of three fluid supply branch lines. ESFR sprinklers are designed for a rapid activation. As the name indicates, the theory behind ESFR is to deliver a sufficient quantity of water during the early stages of fire development in order to suppress the fire. Thus, in order to achieve the goal of early suppression, ESFR sprinklers must quickly generate a sufficient quantity of water capable of penetrating the fire plume and thus be delivered to the core of the fire.
For a fire sprinkler system to be approved for suppression performance it is typically demonstrated to the AHJ that the system and its equipment, including its fire protection sprinklers, are suitable for suppression performance. To facilitate the AHJ approval process, fire protection equipment can be “listed,” which as defined by NFPA 13, means that the equipment is included in a list by an organization that is acceptable to the AHJ and whose list states that the equipment “meets appropriate designated standards or has been tested and found suitable for a specified purpose.” One such listing organization includes, Underwriters Laboratories Inc. (“UL”). UL 1767 Standard for Safety Early-Suppression Fast Response Sprinklers (4th ed. 2013, rev. 2015) from Underwriters Laboratories Inc. (“UL1767”) provides the water distribution and fire test standards to establish that a sprinkler is suitable for early suppression fast response performance under applicable installation guidelines.
FM approved storage sprinklers are subject to the FM Approvals “Approval Standard for Quick Response Storage Sprinklers for Fire Protection—Class Number 2008” (February 2018) (“FM 2008”) from FM Approvals LLC. FM Approved Storage Sprinklers, under FM 2008, are tested to determine suitability for a specified use, i.e., ceiling-level storage protection providing suppression performance Like UL 1767, FM 2008 provides the water distribution and fire test standards to establish that a given sprinkler is suitable for ceiling-level suppression performance for storage protection under applicable installation guidelines.
The installation, listing and/or approval guidelines and standards require consideration of several characteristics of the sprinkler for application and compliance. Sprinkler characteristics include: the orifice size or nominal K-factor of the sprinkler, the installation orientation (pendent or upright), the thermal sensitivity or response time index (RTI) rating of the sprinkler, the sprinkler deflector details and the sprinkler spacing or coverage. Generally, automatic fire protection sprinklers include a solid metal body connected to a pressurized supply of water, and some type of deflector spaced from the outlet is used to distribute fluid discharged from the body in a defined spray distribution pattern over the protected area. The discharge or flow characteristics from the sprinkler body is defined by the internal geometry of the sprinkler including its internal passageway, inlet and outlet (the orifice). As is known in the art, the K-factor of a sprinkler is defined as K=Q/P1/2, where Q represents the flow rate (in gallons/min GPM) of water from the outlet of the internal passage through the sprinkler body and P represents the pressure (in pounds per square inch (psi.)) of water or firefighting fluid fed into the inlet end of the internal passageway though the sprinkler body.
The spray pattern or distribution of a firefighting fluid from a sprinkler defines sprinkler performance. Several factors can influence the water distribution patterns of a sprinkler including, for example, the shape of the sprinkler frame, the sprinkler orifice size or discharge coefficient (K-factor), and the geometry of the deflector. The deflector is typically spaced from the outlet of the body. The deflector geometry is particularly significant since the deflector is the main component of the sprinkler assembly and to a great extent, defines the size, shape, uniformity, and water droplet size of the spray pattern.
To control fluid discharge from the sprinkler body is a fusible or thermally responsive trigger assembly which secures a seal over the central orifice. When the temperature surrounding the sprinkler is elevated to a pre-selected value indicative of a fire, the trigger assembly releases the seal and water flow is initiated through the sprinkler. The thermal sensitivity of the trigger assembly and sprinkler is measured or characterized by Response Time Index (“RTI”), measured in units of (m−s)1/2. Under the FM 2008 standard, an RTI of 80 (m−s)1/2 to 350 (m−s)1/2 [145-635 (ft.*s)1/2] defines a “Standard Response Sprinkler and an RTI equal to or less than 50 (m−s)1/2 [90 (ft.*s)1/2] defines a “Quick Response Sprinkler.” Under the standard, a “Quick Response Sprinkler” with a nominal K-factor of 14 or larger has an RTI of 19 to 36 (m−s)1/2 [35-65 (ft.*s)1/2]. Under UL1767 an Early Suppression Fast Response Sprinkler has an RTI of no more than 36 (m−s)1/2 [65 (ft.*s)1/2].
There are generally two types of thermally responsive trigger assemblies: frangible and non-frangible. Frangible trigger assemblies generally include a liquid-filled frangible glass bulb that shatters upon reaching its rated temperature. Non-frangible trigger assemblies can include fusible links or soldered mechanical arrangements in which the components of the assembly separate upon fusion of the solder reaching its rated temperature. One type of fusible link arrangement includes a strut and a lever or multiple pin arrangement held together by a fusible link to support a sealing assembly within the discharge orifice of the sprinkler. Examples of such fusible link arrangements are shown and described in U.S. Pat. Nos. 8,353,357 and 7,766,252 and U.S. Patent Application Publication Nos. 2011/0121100 and 2005/0224238. The strut and lever are held by the fusible link in an assembled orientation which transfers a compressive force of a load member acting on the strut lever arrangement to the seal assembly. Upon fusion of the solder material and separation of the fusible link in the presence of a sufficient level of heat or fire, the lever and strut members collapse and the sprinkler is actuated with the seal released to initiate the discharge of fluid.
As ceiling heights increase and/or storage hazards extends to higher levels, fire protection from ceiling-level sprinklers only becomes more difficult to achieve and thus, the installation guidelines have limits as to “ceiling-only” storage fire protection. At higher heights there are multiple variables such as for example water supply, the orifice size and deflector details that can alter expected system performance. For example, FM 8-9 and NFPA 13 limits ceiling-only suppression performance fire protection system design guidelines to a maximum ceiling height of forty-five feet (45 ft.) in the protection of commodities classified up to class 4 and cartoned unexpanded plastics. Moreover, for pendent sprinklers beneath a ceiling height of over 30 ft., the FM 8-9 guidelines limit sprinkler linear sprinkler spacing to a range from 8 to a maximum fourteen feet (14 ft.) depending upon the responsiveness of the sprinkler. Accordingly, those of ordinary skill in the art understand that certain conditions under the installation guidelines fail to provide predictability under increasing challenging conditions, such as increased height or higher challenge commodity.
For storage occupancies having ceiling heights over 45 ft., the installation guidelines require system modifications such as for example, (i) installation of a lower “false ceiling” which effectively eliminates storage capacity under the ceiling or (ii) the use of “in-rack” sprinklers, which eliminates “ceiling-only” protection. Using in-rack sprinklers presents its own logistical constraints and/or operational drawbacks such as, for example, (i) changing or modifying the rack to install the in-rack sprinklers may require a modification of the sprinkler system; (ii) moving a rack to install in-rack sprinklers may require modifying the sprinkler system; and/or (iii) there is a risk of damaging an in-rack sprinkler occurs when loading or unloading a storage bay, in particular when employing a fork lift.
There are also known commercially available sprinklers that provide for suppression mode ceiling-only protection ceiling heights over 45 ft. with specific installation criteria not available under the general installation guidelines. For example, one known system is for rack storage of up to 43 ft. under a maximum ceiling height of 48 ft. The commercially available sprinkler and system is described in Technical Data Sheet Form No. F_010715 Rev. 18.1: Specific Application Early Suppression Fast Response (ESFR) 28.0 K-factor VK514 pendent sprinkler from The Viking Corporation of Hastings, Mich. As of January 2019, it is believed that FM has indicated approval for ceiling-only system designs for the protection of Class I-IV and cartoned unexpanded plastics single-row and double row rack storage that qualifies as open frame with aisle widths at a 6 ft minimum beneath a maximum ceiling height of up to 50 ft. These designs using either: (i) Quick Release K25.2 Pendent Storage Sprinklers; or (ii) Quick Release K22.4 Pendent Storage Sprinklers. Examples of commercially available K25.2 and K22.4 sprinklers are described respectively in Technical Data Sheet Form No. F_0100102 (19.04.19 Rev. 19.1): ESFR Pendent Sprinkler VK510 (K25.2) and Technical Data Sheet Form No. F_081612 (18.10.11 Rev. 18.2): ESFR Pendent Sprinkler VK506 (K22.4) each of which is from The Viking Corporation of Hastings, Mich.
With businesses and building owners interested in increasing storage capacity vertically with higher ceiling and storage heights, there remains a need to identify and provide ceiling-only suppression fire protection sprinkler systems for high hazard rack storage at heights beyond those available under the known commercial systems and present installation standards. Because of limitations in current commercial systems and industry guidance, there remains a need for ceiling-only fire protection systems for rack storage of high hazards commodities under ceiling heights over 45 feet and more particularly under maximum ceiling heights of 50 ft. and over. However heretofore, in light of the various parameters to be selected from water supply, sprinkler orifice size and sprinkler deflector configuration, such systems have yet to be realized.